A crystallographic study of dislocation cell arrangement in aluminium deformed at an elevated temperature

The arrangement of dislocation cells in a commercial aluminium alloy 1145 subjected to uniaxial tensile deformation at 150 °C to a true strain of 0.1 has been investigated using transmission electron microscopy and convergent beam electron diffraction. Both misorientations between neighbouring dislocation cells and misorientation gradients across the grain as well as dislocation boundary orientations have been analysed. As an example, illustrating general qualitative features of the deformation microstructure as a whole, results of a detailed crystallographic analysis of a typical cell arrangement are presented. The results obtained in the study are compared to those available for similar deformation conditions at room temperature and the validity of some assumptions from the theory of low-energy dislocation structures is discussed. It is concluded that the observed cell structure has a complex hierarchical character and neither misorientation vector distributions nor dislocation boundary orientations correspond to the simple checker-board arrangement of cells predicted by the above theory.